Flue.



Patented Aug. 7, I900. w. A. GAY.

F L U E (Application filed Sept. 18, 1899.)

(No Model.)

WITNESSES ATTORNEY NTTnn STATES PATENT OFFICE.

WILLIAM A. GAY, or NEWARK, new JERSEY.-

FLUE.

SPECIFICATION forming part of Letters Patent No. 655,619, dated August 7, 1900.

Application filed September 18, 1899. Serial No. 730,315. (No model.)

T0 aZZ whom it map concern:

Be it known that l, IVILLIAM A. GAY, a citizen of the United States, residing at Newark, Essex county, New Jersey, have invented certain new and useful Improvements in Flues, of which the following is a specification.

This invention relates to flues, such as stovepipe-flues and dues in chimneys, stacks, &c. and the object of the invention is to provide a simple and inexpensive means of utilizing the back or down draft, so as to enhance combustion, to avoid wholly, or nearly so, the formation of smoke and soot, and to improve the draft of the flue.

In the accompanying drawings, which illustrate an embodiment of the invention, Figure 1 is a longitudinal axial section of a stovepipe provided with my invention, and Fig. 2 is an end view of the same.

A represents a length or section of ordinary Stovepipe. This pipe may be, say, six inches in diameter and twenty-six inches long. In the pipe A and fixed about concentrically therewith are two alined sections B B, of sheetmetal pipesay about four inches and a half in diameter and about ten and one-half inches long. These sections B when placed as shown in the drawings leave an annular space at about them and between them and the pipe A of about three-quarters of an inch in width, and between the ends of the alined sections will be left a space y. Preferably the upper ends of the alined sections B will be slightly turned inward, as seen at b, so that the upper edge of the lower section may be just within the space included by the lower end of the next section above. Of course this does not apply to the extreme upper section B in the flue; but in Fig. 1 the construction is such that two pipe-sections A, each pro vided with inner sections B, may be jointed together in the usual way. The sections B may of course be mounted in the pipe A by any convenient means. As shown in Fig. 1, strips of metal Ct are riveted to the sections B and their ends bent outward and riveted to the pipe A. There may be any convenient number of these strips. Three or four will suflice.

The invention may be adapted. to chimneyfiues as well as stovepipes, in which case the pipe-sections B may have the same cross-section as the flue and may be of any suitable material, such as sheet-metal or ceramic material.

The concentrically arranged and alined pipe-sections in the flue serve to prevent the form at-ion of soot and smoke almost entirely. They enhance the draft and efiect an important economy in fuel, and it is believed that these beneficial results are due to the fact that the construction efiects the return of a considerable proportion of the uncombined or only partially-combined gases to the fire instead of permitting them to escape at the top of the flue or permitting the deposition of carbon therefrom in the form of soot on the walls of the flue. It is well known that the gaseous products of combustion vary greatly both in temperature and density, those most perfectly or fully combined being the hottest and in that exhausted condition much lighter thanthe outer air. These latter rise rapidly and mingle quickly with the outer air. Others more dense and carrying much uncombined carbonaceous matter are unable to force their way from the flue and depositcarbon in the form of soot therein. From a consideration of these facts it will be understood that in the upward passage of the products of combustion through the flue the hotter gases will flow along the axis of the flue with considerable rapidity and force, while the less-heated and heavier gases, more sluggish in their nature, will be crowded out ward until the heaviest are condensed against the less-heated wall of the flue, or they will descend to a hotter point, where they will be partially combined, broken up, and reheated.-

lVith the flue constructed as herein described the hotter and more completely combined gases crowd the heavier gases out laterally into the annular space so at the points y, and these heavier gases descend in the space w by their own gravity. Being relieved from friction with the upward current of the hotter gases, which tends to draw them upward, they are more speedily and with greater certainty carried down and back to the combustion chamber, where they are finally consumed. This I believe to be the correct ra tionale of the operation of my flue.

I have given above convenient dimensions for the parts, and particularly for the parts when applied to astove or furnace pipe; but I do not mean by this to restrict myselt'to these dimensions'and proportions at all. The invention resides in the formation with a flue of an outer annular space or passage connected at suitable intervals with the main central passage, this being effected by the alined tubular sections B, with apertures or spaces y between them, as shown, for the lateral expulsion of the heavier gases. As herein shown, the apertures y are formed simply by spaces between the ends of pi pe-sections; but obviously this is only one way of effecting what may be done in other ways as well.

I have described my invention as applied to stovepipes, chimneys, and stacks of various kinds; but it will be understood that I do not limit-myself to any particular kind of furnace-flue. The invention may be applied to locomotives, steamships, '&c., as well.

I am aware, of course, that the employment of means at the top of a chimney-flue to assist the entry of air next the flue-wall is not new, and this I do not claim. In this device, however,no separating-partition has been provided between the two currents of gasesthe ascending axial highly-heated current and the descending outer less-heated currentespecially at the point where such a partition is most required, which is near the point of combustion, where the hot gases enler the flue. I find that'much improved results are obtained where there is interposed between the ascending current and the annular descending current, and especially down near the furnace or fire-box, a partition which prevents the direct transmission of the heat from the inner to the outer current, apertures being provided, however, at suitable intervals in said partition to permit the heavier gases to be crowded outward radially. These improved results I believe to be due to the fact that the outer wall of the fine is kept at a lower temperature and the outer current of gases thus reduced in temperature correspondingly, whereby contraction and condensation are attained and the downward flow of the exterior current accelerated. It will be obvious that where the two currents of gases are in direct contact the outer current must partake of the heat of the axial current by direct transmission,

and its gases will thus be expanded and the downward flow checked.

While my invention contemplates the ex tension of the apertured partition throughout the entire length of the flue, its greatest at intervals in their length through the me- I dium of apertures in the partition separating them, substantially as set forth.

2. A pipe or stack for products of combustion, comprising an outer inclosing wall, and a series of alined inner pipe-sections within said outer wall, the said inner pipe-sections being of less diameter than the main line, whereby an exterior down-flue x, is formed, and having spaces or apertures y between their ends whereby, the said exterior flue communicates with the axial flue within said pipe-sections, substantially as set forth.

3. The combination with a stovepipe A, which provides an upright flue for products of combustion, of alined pipe-sections B, secured in said pipe A, said sections being of less diameter than the pipe A, so as to form an external, down-flue as, and having spaces or apertures at y whereat the axial flue in the sections B communicates with the external flue a2, substantially as set forth.

4. The combination with a pipe or stack having in it a flue for products of combustion, of the alined pipe-sections B mounted in the fine in said pipe or stack, said sections 13 being axially situated in and of less diameter than the flue, having spaces y between their ends, and being slightly reduced in diameter at their upper ends, substantially as set forth.

In witness whereof I have hereunto signed my name, this 11th day of September, 1899, in the presence of two subscribing witnesses.

IVILLIAM A. GAY.

IVitnesses-z HENRY OoNNnTr, PETER A. Ross. 

